A high light transmittance foaming material and preparation method thereof

Abstract

The present invention provides a high-transmittance foam material and a preparation method thereof, and relates to the technical field of foam materials. The preparation method of the high-transmittance foam material provided by the present invention comprises the following steps: ultrasonically mixing a body to be foamed and a co-foaming agent to obtain a swollen body to be foamed; foaming the swollen body to be foamed to obtain a high-transmittance foam material; the foaming includes supercritical fluid foaming or heating foaming. The preparation method of the present invention is simple, and the obtained foam material has high light transmittance. The light transmittance of the high-transmittance foam material prepared by the present invention is above 85%, and the haze is above 50%, which meets the requirements of various applications for light transmission and scattering.

Description

Technical Field

[0001] The invention relates to the technical field of foaming materials, and in particular to a high-light-transmittance foaming material and a preparation method thereof. Background Art

[0002] In recent years, the public's expectations for the functional design of materials have led to an increasing demand for translucent materials. Polymer foam translucent materials are used in daily life due to their high light transmittance and possible high scattering properties, such as replacing glass as a transparent element in natural lighting structure buildings, as a high-transmittance shoe foam designed as a lighting function, a protective screen for display screens with luminous functions, lampshade materials with different light transmittance requirements, and privacy protection materials with a frosted texture, etc.

[0003] In the thermoplastic polymer foaming process, it can be divided into two categories: chemical foaming and physical foaming according to the difference in the gas generation principle. Chemical foaming is to release gas through chemical reaction or thermal decomposition under foaming processing conditions to form holes, but the emission of harmful substances in the foaming process, the pollution of foam products by residual chemical foaming agents and the low multiples seriously limit the application. Traditional physical foaming usually uses hydrocarbons (such as propane, butane, pentane, etc.), low-boiling hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) as foaming agents, but the gases produced by these physical foaming agents will cause ozone layer damage and greenhouse effect, as well as safety and environmental protection issues such as flammability and explosion, which make them not widely accepted.

[0004] At present, in the field of foaming polymers, supercritical fluids have become a new type of foaming agent that replaces chemical foaming agents and traditional physical foaming agents, especially supercritical nitrogen (N2) and carbon dioxide (CO2) as foaming agents. With the development of society, its green and environmentally friendly characteristics have been deeply rooted in the hearts of the people. Supercritical fluid foaming polymers have also begun to be mass-produced in recent years, and higher-demand supercritical fluid foaming technology has also been increasingly expected. However, the pore morphology of the foam material prepared by this method usually has the characteristics of small pore size and high pore density. The microporous foam prepared by this technology is not conducive to light refraction, so the prepared foam is basically opaque, and it is difficult to meet the requirements for material transmittance and haze.

[0005] Chinese patent CN201910011816.7 discloses a molding process for a highly light-transmitting foamed elastic material. This solution prepares a highly light-transmitting foamed elastic material by slowly releasing pressure in supercritical fluid foaming, but the pressure release rate is difficult to control in experimental operations, which is not conducive to the precise control of the cell size. Chinese patent CN202111464400.4 discloses a highly light-transmitting, high-fog light diffuser plate and its preparation method and application. This solution uses a chemical foaming method to prepare a highly light-transmitting, high-fog foam material, but the operation time in the early pretreatment stage is too long, and the decomposition of the chemical foaming agent during the foaming process will cause damage to the environment. Summary of the invention

[0006] The object of the present invention is to provide a highly light-transmitting foam material and a preparation method thereof. The preparation method of the present invention is simple, and the obtained foam material has high light transmittance.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a highly light-transmitting foam material, comprising the following steps:

[0009] Ultrasonic mixing of the body to be foamed and the co-foaming agent to obtain a swollen body to be foamed;

[0010] foaming the swollen body to be foamed to obtain a highly light-transmitting foamed material;

[0011] The foaming includes supercritical fluid foaming or heating foaming.

[0012] Preferably, the ultrasonic mixing time is d×(10-120) min, where d is the thickness or radius of the foamed body.

[0013] Preferably, the ultrasonic power of the ultrasonic mixing is 500-1500W.

[0014] Preferably, the body to be foamed includes one or more of thermoplastic polyurethane elastomer, thermoplastic polyester elastomer, thermoplastic polyamide elastomer, thermoplastic polyolefin elastomer, polystyrene, polymethyl methacrylate and polycarbonate.

[0015] Preferably, when the foamed body is a crystalline polymer, the foaming temperature is (Tm-50°C) to Tm, where Tm is the melting temperature of the crystalline polymer;

[0016] When the foamed body is an amorphous polymer, the foaming temperature is (Tg-50°C) to (Tg+60°C), where Tg is the glass transition temperature of the amorphous polymer.

[0017] Preferably, the co-foaming agent includes one or more of water, methanol, ethanol, acetone, ether, dichloromethane and tetrahydrofuran.

[0018] Preferably, the foaming time of the supercritical fluid is d×(10-60) min, where d is the thickness or radius of the foamed body.

[0019] Preferably, the heating foaming includes oil bath foaming or microwave foaming.

[0020] Preferably, the heating and foaming time is 10 to 120 seconds.

[0021] The present invention provides a highly light-transmitting foam material prepared by the preparation method described in the above technical solution.

[0022] The present invention provides a method for preparing a highly transparent foaming material. Before the supercritical fluid is foamed, the co-foaming agent is ultrasonically introduced into the body to be foamed to make the body to be foamed swell, and then the foaming technology is used to prepare a foaming material with coarse pores and high light transmittance. When the conventional foaming method is used, the amount of the co-foaming agent dissolved by the body to be foamed is limited. Therefore, in the foaming process, the foaming agent is usually mainly supercritical carbon dioxide or supercritical nitrogen. The co-foaming agent only plays an auxiliary role, and the pores are relatively small; after the ultrasonic treatment of the present invention, more co-foaming agents can enter the body to be foamed. At this time, the co-foaming agent and the foaming agent play a role at the same time during the foaming process, so the pores of the foaming material become larger, thereby improving the light transmittance of the material. The light transmittance (the material's ability to transmit light) of the highly transparent foaming material prepared by the present invention is above 85%, and the haze (the material's ability to scatter light) is above 50%, which meets the requirements of various applications for light transmission and scattering.

[0023] Traditional foaming materials only have the function of lightweighting but are not light-transmissive. The present invention only needs ultrasonic swelling before foaming to prepare a foaming elastic material with high light transmittance. The high light transmittance foaming material provided by the present invention can replace the glass commonly used in natural lighting structure buildings as a transparent structural element, as a high light transmittance shoe foam designed for lighting functions, a protective screen for display screens with light-emitting functions, a lampshade material with different light transmittance requirements, and a privacy protection material with a frosted texture, etc., to meet various light transmittance requirements.

[0024] The present invention adopts a supercritical fluid foaming or heating foaming process, and only one step is required to make the co-foaming agent quickly swell in the foamed body, thereby solving the problem of long saturation time required after adding the co-foaming agent, and the prepared foaming material can achieve high light transmittance and high haze requirements that cannot be achieved by foaming materials at this stage. The preparation method of the present invention has a simple process, shortened foaming time, and a relatively high foaming ratio, and solves the technical difficulties of high light transmittance and high haze of coarse-pore foaming materials, providing a material basis for enriching the product categories of foaming materials and the design of foaming materials with special functions, having practical significance and promotion value, and is expected to produce good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the preparation process of the high light transmittance foaming material in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a highly light-transmitting foam material, comprising the following steps:

[0027] Ultrasonic mixing of the body to be foamed and the co-foaming agent to obtain a swollen body to be foamed;

[0028] foaming the swollen body to be foamed to obtain a highly light-transmitting foamed material;

[0029] The foaming includes supercritical fluid foaming or heating foaming.

[0030] In the present invention, unless otherwise specified, the raw materials used for preparation are all commercially available products.

[0031] The present invention ultrasonically mixes the body to be foamed and the co-foaming agent to obtain a swollen body to be foamed. In the present invention, the body to be foamed preferably includes one or more of thermoplastic polyurethane elastomer (TPU), thermoplastic polyester elastomer (TPEE), thermoplastic polyamide elastomer (TPA), thermoplastic polyolefin elastomer (TPO), polystyrene (PS), polymethyl methacrylate (PMMA) and polycarbonate (PC). In the present invention, the body to be foamed is a particle or a sheet.

[0032] In the present invention, the co-foaming agent preferably includes one or more of water, methanol, ethanol, acetone, ether, dichloromethane and tetrahydrofuran.

[0033] In the present invention, the usage ratio of the to-be-foamed body and the co-foaming agent is preferably 1 g: 3 to 15 mL, more preferably 1 g: 5 to 10 mL.

[0034] In the present invention, the ultrasonic mixing time is preferably d×(10-120) min, more preferably d×(10-30) min, where d is the thickness or radius of the body to be foamed, and the unit of d is mm. In the present invention, when the body to be foamed is in sheet form, d is the thickness of the body to be foamed; when the body to be foamed is in granular form, d is the radius of the body to be foamed. In the present invention, a shorter ultrasonic time will result in uneven distribution of the co-foaming agent in the body to be foamed. The ultrasonic mixing time of the present invention can make the body to be foamed reach the swelling limit state. Too long ultrasonic time will result in a waste of resources.

[0035] In the present invention, the ultrasonic power of the ultrasonic mixing is preferably 500-1500W, more preferably 900W.

[0036] In the present invention, the ultrasonic mixing preferably includes: placing the body to be foamed and the co-foaming agent in a sealed plastic container at the same time, and then placing the sealed plastic container in an ultrasonic device for ultrasonication. In the present invention, the ultrasonic device is preferably an ultrasonic cleaning machine. In a specific embodiment of the present invention, the ultrasonic cleaning machine has a water tank inside, the water tank is filled with water, the sealed plastic container containing the body to be foamed and the co-foaming agent is placed in the water, and the bottom of the water tank sends ultrasonic waves to drive the water, and then drives the object to be ultrasonicated to be ultrasonicated.

[0037] In the present invention, the calculation method of the dissolved amount of the co-foaming agent is shown in Formula 1:

[0038] s = m1 / (m2-m1) × 100%, formula 1;

[0039] In the formula 1, s is the dissolved amount of the co-foaming agent; m1 is the mass of the body to be foamed; and m2 is the mass of the swollen body to be foamed.

[0040] After obtaining the swollen body to be foamed, the present invention foams the swollen body to be foamed to obtain a highly light-transmitting foamed material. In the present invention, the foaming includes supercritical fluid foaming or heating foaming. In the present invention, supercritical fluid foaming is a conventional foaming method, which has the advantages of mature technology and easy control of pore size; the foaming principle of heating foaming is similar to that of supercritical fluid foaming, which has the advantages of no high-pressure operation, which is not only safer, but also shortens the operation time.

[0041] In the present invention, when the body to be foamed is a crystalline polymer (such as TPU, TPEE, TPA, TPO), the foaming temperature is preferably (Tm-50°C) to Tm, more preferably (Tm-40°C) to (Tm-10°C), and further preferably (Tm-30°C) to (Tm-20°C), where Tm is the melting temperature of the crystalline polymer, in °C. In the present invention, when the body to be foamed is an amorphous polymer (PS, PMMA, PC), the foaming temperature is preferably (Tg-50°C) to (Tg+60°C), more preferably (Tg-20°C) to (Tg+40°C), and further preferably Tg to (Tg+20°C), where Tg is the glass transition temperature of the amorphous polymer, in °C. In the present invention, the foaming temperature can enable the body to be foamed to have a suitable melt strength, which is beneficial to the foaming of the body to be foamed.

[0042] The following is a detailed description of supercritical fluid foaming:

[0043] In the present invention, the supercritical fluid foaming preferably includes: placing the swollen body to be foamed in a reactor heated to the foaming temperature, adding a supercritical fluid into the reactor, the saturated pressure in the reactor is 5 to 30 MPa, performing supercritical fluid foaming, and then releasing the pressure to obtain a highly light-transmittance foaming material.

[0044] In the present invention, the supercritical fluid is a conventional fluid for supercritical foaming in the art, such as supercritical carbon dioxide and / or supercritical nitrogen.

[0045] In the present invention, the saturation pressure is more preferably 10-30 MPa, and further preferably 15 MPa. The present invention adopts the above saturation pressure, which is more conducive to the dissolution of the supercritical fluid.

[0046] In the present invention, the foaming time of the supercritical fluid is preferably d×(10-60) min, more preferably d×(15-20) min, where d is the thickness or radius of the body to be foamed, and the unit is mm. The present invention controls the above time so that the body to be foamed is in a gas saturated state, that is, the foaming time of the supercritical fluid is the saturation time of the swollen body to be foamed in the reactor. As a specific embodiment, the supercritical fluid foaming time of a 2mm thick sheet sample is 30min. In order to ensure that the supercritical fluid is completely saturated in the body to be foamed, the saturation time should not be too short. Too long a saturation time not only wastes time, but also may cause excessive diffusion of the co-foaming agent and fail to meet product requirements.

[0047] In the present invention, the rate of the pressure relief is preferably 0.1 to 1000 MPa / s, more preferably 50 to 400 MPa / s, and further preferably 100 MPa / s. In the pressure relief process of the present invention, the foaming agent (supercritical fluid) and the co-foaming agent in the gas-saturated state inside the foamed body are rapidly released, thereby forming a highly light-transmitting foaming material. In the present invention, a faster pressure relief rate is easy to form a pore structure with a wider pore size distribution, thereby obtaining a foaming material with more uniform pores.

[0048] The following is a detailed description of heating foaming:

[0049] In the present invention, the heating foaming preferably includes oil bath foaming or microwave foaming.

[0050] In the present invention, when the foamed body is a crystalline polymer (such as TPU, TPEE, TPA, TPO), the foaming temperature is preferably (Tm-50°C) to Tm, more preferably (Tm-40°C) to (Tm-10°C), and further preferably (Tm-30°C) to (Tm-20°C), where Tm is the melting temperature of the crystalline polymer, in °C. In the present invention, when the foamed body is an amorphous polymer (PS, PMMA, PC), the foaming temperature is preferably (Tg-50°C) to (Tg+60°C), more preferably (Tg-20°C) to (Tg+40°C), and further preferably Tg to (Tg+20°C), where Tg is the glass transition temperature of the amorphous polymer, in °C. In the present invention, the oil bath foaming time is preferably 10 to 120 s, and more preferably 30 to 60 s. In the present invention, a shorter foaming time will result in the co-foaming agent being unable to diffuse out of the polymer matrix in time, while a longer foaming time will cause the pores inside the foam to completely collapse during the foaming process due to the low strength of the polymer melt, and the expansion ratio of the foaming material will be reduced.

[0051] In the present invention, the microwave power of the microwave foaming is preferably 300-1000W, more preferably 300-600W; the microwave foaming time is preferably 10-120s, more preferably 10-60s. In the present invention, the microwave power is inversely proportional to the time. The increase of microwave power and time in the microwave oven can increase the energy in the system, thereby promoting the temperature increase of the swollen foam body. Therefore, the control of power and time during the microwave foaming process should be balanced and coordinated. In the present invention, a smaller microwave power cannot achieve the temperature required for foaming of the foam body, and a larger microwave power produces a too fast heating rate, which will make it difficult to control the overall temperature rise, so that the prepared foam cells will present an uneven state. When the microwave power is 300-600W, the microwave foaming time is preferably 10-60s.

[0052] The invention uses heating and foaming to rapidly release the co-foaming agent in the gas-saturated body to be foamed.

[0053] In the present invention, after the heating and foaming, the foamed body is preferably subjected to a cold water bath to obtain a highly light-transmitting foamed material. In the present invention, the temperature of the cold water bath is preferably 20° C.; the time of the cold water bath is preferably 1 minute. The present invention utilizes a cold water bath to stabilize the pores of the foamed material.

[0054] The present invention provides a highly light-transmittance foamed material prepared by the preparation method described in the above technical solution. In the present invention, the light transmittance of the highly light-transmittance foamed material is preferably above 85%. In the present invention, the haze of the highly light-transmittance foamed material is preferably above 50%. In the present invention, the pore diameter range of the highly light-transmittance foamed material is preferably 0.1 to 6 mm, more preferably 3 mm.

[0055] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Example 1

[0057] Take a commercially available thermoplastic polyurethane elastomer (TPU, 1180A, density 1.16 g / cm 3 , Tm is 148.7℃, purchased from BASF) into a sheet with a size of 10mm×10mm×2mm (thickness is 2mm); weigh the initial mass of TPU, recorded as m1; put the TPU to be foamed into a closed plastic container filled with co-foaming agent acetone, use an ultrasonic device to ultrasonicate for 120min, the ultrasonic power is 900W, so that the TPU to be foamed is in a swollen state; take out the TPU from the acetone and weigh the mass again, recorded as m2, and calculate the dissolved amount s of the co-foaming agent according to the formula s=m1 / (m2-m1)×100%;

[0058] The swollen TPU to be foamed is then quickly placed in a reactor heated to 130°C in an oil bath, and supercritical CO2 is added to the reactor through a pressurizing device, where the saturation pressure in the reactor is 15MPa; the TPU is saturated in the reactor for 30 minutes until the body to be foamed is in a gas saturated state; the pressure in the autoclave is then released at a pressure release rate of 100MPa / s, and after cooling and shaping, a highly light-transmitting foaming material is obtained.

[0059] Example 2

[0060] The preparation method is basically the same as that of Example 1, except that the ultrasonic time is adjusted from "120 min" to "60 min".

[0061] Example 3

[0062] The preparation method is basically the same as that of Example 1, except that the foaming temperature is adjusted from "130°C" to "120°C".

[0063] Example 4

[0064] The preparation method is basically the same as that of Example 1, except that the saturated pressure in the reactor is adjusted from "15 MPa" to "20 MPa".

[0065] Example 5

[0066] The preparation method is basically the same as that of Example 1, except that the saturation time is adjusted from "30 min" to "40 min".

[0067] Example 6

[0068] The preparation method is basically the same as that of Example 1, except that the pressure relief rate is adjusted from "100 MPa / s" to "50 MPa / s".

[0069] Example 7

[0070] The preparation method is basically the same as that of Example 1, except that the co-foaming agent is adjusted from "acetone" to "ethanol".

[0071] Example 8

[0072] Take a commercially available thermoplastic polyurethane elastomer (TPU, 1180A, density 1.16 g / cm 3 , Tm is 148.7℃, purchased from BASF) into a sheet with a size of 10mm×10mm×2mm (thickness is 2mm); weigh the initial mass of TPU, recorded as m1; put the TPU to be foamed into a sealed plastic container filled with co-foaming agent acetone, use an ultrasonic device to ultrasonicate for 120min, and the ultrasonic power is 900W to make the TPU to be foamed in a swollen state; take out the TPU from the acetone and weigh the mass again, recorded as m2, and calculate the dissolved foaming agent s according to the formula s=m1 / (m2-m1)×100%;

[0073] Then, the swollen TPU to be foamed is quickly placed in an oil bath at 130°C and foamed for 30 seconds to quickly release the co-foaming agent acetone in the gas-saturated state inside the body to be foamed; the foamed body is quickly taken out of the oil bath and placed in a cold water bath at 20°C for 1 minute to keep the bubbles stable. After cooling and shaping, a highly light-transmitting foamed material is obtained.

[0074] Example 9

[0075] Take a commercially available thermoplastic polyurethane elastomer (TPU, 1180A, density 1.16 g / cm 3 , Tm is 148.7℃, purchased from BASF) into a sheet with a size of 10mm×10mm×2mm (thickness is 2mm); weigh the initial mass of TPU, recorded as m1; put the TPU to be foamed into a sealed plastic container filled with co-foaming agent acetone, use an ultrasonic device to ultrasonicate for 120min, and the ultrasonic power is 900W to make the TPU to be foamed in a swollen state; take out the TPU from the acetone and weigh the mass again, recorded as m2, and calculate the dissolved foaming agent s according to the formula s=m1 / (m2-m1)×100%;

[0076] Then, the swollen TPU to be foamed is quickly placed in a microwave oven and heated at a microwave power of 600 W for 30 seconds, so that the co-foaming agent acetone in the gas-saturated state inside the foam to be foamed is quickly released; the foamed body is quickly taken out of the microwave oven and placed in a cold water bath at a temperature of 20°C for 1 minute to keep the bubbles stable. After cooling and shaping, a highly light-transmitting foaming material is obtained.

[0077] Example 10

[0078] The preparation method is basically the same as that of Example 8, except that the ultrasonic time is adjusted from "120 min" to "60 min".

[0079] Embodiment 11

[0080] The preparation method is basically the same as that of Example 8, except that the foaming temperature is adjusted from "130°C" to "120°C".

[0081] Comparative Example 1

[0082] Commercially available thermoplastic polyurethane elastomer (TPU, 1180A, density 1.16 g / cm 3 , Tm is 148.7℃, purchased from BASF) is made into a sheet with a size of 10mm×10mm×2mm (thickness is 2mm), placed in a reactor heated to 130℃ in an oil bath, and then supercritical CO2 is added to the reactor through a pressurizing device, and the saturation pressure in the reactor is 15MPa; the TPU is saturated in the reactor for 30min until the foamed body is in a gas saturated state; then the pressure in the autoclave is released at a pressure release rate of 100MPa / s, and after cooling and shaping, a high-transmittance foaming material is obtained.

[0083] Comparative Example 2

[0084] Commercially available thermoplastic polyurethane elastomer (TPU, 1180A, density 1.16 g / cm 3 , Tm is 148.7℃, purchased from BASF) is made into a sheet with a size of 10mm×10mm×2mm (thickness is 2mm); the TPU to be foamed and 10mL of acetone are placed in a reactor heated to 130℃ in an oil bath, and then supercritical CO2 is added to the reactor through a pressurizing device, and the saturation pressure in the reactor is 15MPa; the TPU is saturated in the reactor for 30min until the foam is in a gas saturated state; then the pressure in the autoclave is released at a pressure release rate of 100MPa / s, and after cooling and shaping, a high-transmittance foaming material is obtained.

[0085] Comparative Example 3

[0086] The preparation method is basically the same as that in Example 1, except that "ultrasonication for 120 minutes using an ultrasonic device" is adjusted to "standing for 120 minutes without ultrasonication".

[0087] Example 12

[0088] The preparation method is basically the same as that of Example 1, except that the ultrasonic time is adjusted from "120 min" to "10 min".

[0089] Embodiment 13

[0090] The preparation method is basically the same as that of Example 1, except that the foaming temperature is adjusted from "130°C" to "90°C".

[0091] Embodiment 14

[0092] The preparation method is basically the same as that of Example 1, except that the foaming temperature is adjusted from "130°C" to "170°C".

[0093] Embodiment 15

[0094] The preparation method is basically the same as that of Example 1, except that the saturated pressure in the reactor is adjusted from "15 MPa" to "5 MPa".

[0095] Example 16

[0096] The preparation method is basically the same as that of Example 1, except that the saturation time is adjusted from "30 min" to "10 min".

[0097] Comparative Example 4

[0098] The preparation method is basically the same as that of Example 8, except that "ultrasonication for 120 minutes using an ultrasonic device" is adjusted to "standing for 120 minutes without ultrasonication".

[0099] Embodiment 17

[0100] The preparation method is basically the same as that of Example 8, except that the foaming temperature is adjusted from "130°C" to "170°C".

[0101] Test Case

[0102] The properties of the highly light-transmitting foamed materials prepared in the embodiments and comparative examples are shown in Table 1. Comparative Example 1 lacks the step of saturating the co-foaming agent, the pore size is small, and the light transmittance is poor. Comparative Example 2 adopts the method of saturating the co-foaming agent and the foaming agent at the same time, the co-foaming agent enters the matrix less, the pore size is small, and the light transmittance is poor. Comparative Example 3 lacks the co-foaming agent ultrasonic step, the amount of co-foaming agent entering the matrix is ​​less than that of the ultrasonic method, the pore size is small, and the light transmittance is poor. Comparative Example 4 lacks the co-foaming agent ultrasonic step, the amount of co-foaming agent entering the matrix is ​​less than that of the ultrasonic method, the pore size is small, and the light transmittance is poor. In addition, the amount of co-foaming agent dissolved in Comparative Examples 1 to 4 is small, indicating that the present invention uses ultrasonic swelling to increase the amount of co-foaming agent dissolved, which is beneficial to improve the foaming quality. Further analysis shows that the ultrasonic time of the co-foaming agent in Example 12 is short, the co-foaming agent enters the matrix less, the pore size is small, and the light transmittance is poor. In Example 13, the foaming temperature is too low, and the higher melt strength of the polymer hinders the growth of the bubbles, so foaming cannot be carried out, and the density of the material is too high and the transmittance is low. In Example 14, the foaming temperature is too high, and the melt strength of the polymer is too low to support the bubbles, so foaming cannot be carried out, and the density of the material is too high and the transmittance is low. In Example 15, the saturation pressure is too low, the amount of foaming agent dissolved in the same time is small, and the foaming driving force is insufficient, so foaming cannot be carried out, and the density of the material is too high and the transmittance is low. In Example 16, the saturation time is short, the amount of foaming agent dissolved is small, and the density of the material is too high and the transmittance is low. In Example 17, the foaming temperature is too high, and the melt strength of the polymer is too low to support the bubbles, so foaming cannot be carried out, and the density of the material is too high and the transmittance is low.

[0103] Table 1 Preparation process parameters and performance results of examples and comparative examples

[0104]

[0105]

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a highly light-transmittance foaming material, comprising the following steps: Ultrasonic mixing of the body to be foamed and the co-foaming agent to obtain a swollen body to be foamed; The foamed body is one or more of thermoplastic polyurethane elastomer, thermoplastic polyester elastomer, thermoplastic polyamide elastomer, thermoplastic polyolefin elastomer, polystyrene, polymethyl methacrylate and polycarbonate; The dosage ratio of the foamed body to the co-foaming agent is 1g:3-15mL; The ultrasonic mixing time is d×(10-120) min, where d is the thickness or radius of the foamed body; foaming the swollen body to be foamed to obtain a highly light-transmitting foamed material; When the foamed body is a crystalline polymer, the foaming temperature is (Tm-50°C) to Tm, where Tm is the melting temperature of the crystalline polymer; When the foamed body is an amorphous polymer, the foaming temperature is (Tg-50°C) to (Tg+60°C), where Tg is the glass transition temperature of the amorphous polymer; The foaming includes supercritical fluid foaming or heating foaming.

2. The preparation method according to claim 1, characterized in that: The ultrasonic power of the ultrasonic mixing is 500-1500W.

3. The preparation method according to claim 1, characterized in that: The co-foaming agent includes one or more of water, methanol, ethanol, acetone, ether, dichloromethane and tetrahydrofuran.

4. The preparation method according to claim 1, characterized in that: The foaming time of the supercritical fluid is d×(10-60) min, where d is the thickness or radius of the foamed body.

5. The preparation method according to claim 1, characterized in that: The heating foaming includes oil bath foaming or microwave foaming.

6. The preparation method according to claim 5, characterized in that: The heating and foaming time is 10 to 120 seconds.

7. The highly light-transmittance foamed material prepared by the preparation method according to any one of claims 1 to 6.

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